Enable generation of local host candidate when RTCConfiguration is null.

content/renderer/media/rtc_peer_connection_handler.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/media/rtc_peer_connection_handler.h"
 
 #include <string>
 #include <utility>
 #include <vector>
 
@@ skipping 167 matching lines @@
     description->ToString(sdp);
     *type = description->type();
   }
 }
 
 // Converter functions from WebKit types to WebRTC types.
 
 void GetNativeRtcConfiguration(
     const blink::WebRTCConfiguration& blink_config,
     webrtc::PeerConnectionInterface::RTCConfiguration* webrtc_config) {
-  if (blink_config.isNull() || !webrtc_config)
+  if (!webrtc_config)

[tommi (sloooow) - chröme, 2015/09/16 18:13:40]

Is this even possible? maybe we should just replace this with a DCHECK.

[guoweis_left_chromium, 2015/09/16 18:51:03]

Done.

     return;
-  for (size_t i = 0; i < blink_config.numberOfServers(); ++i) {
-    webrtc::PeerConnectionInterface::IceServer server;
-    const blink::WebRTCICEServer& webkit_server =
-        blink_config.server(i);
-    server.username =
-        base::UTF16ToUTF8(base::StringPiece16(webkit_server.username()));
-    server.password =
-        base::UTF16ToUTF8(base::StringPiece16(webkit_server.credential()));
-    server.uri = webkit_server.uri().spec();
-    webrtc_config->servers.push_back(server);
+
+  // When we don't have WebRTCConfiguration, treat it as a special case where we
+  // should generate local host candidate. This will only be honored if
+  // enable_multiple_routes is disabled.
+  if (blink_config.isNull()) {
+    webrtc_config->enable_localhost_ice_candidate = true;

[tommi (sloooow) - chröme, 2015/09/16 18:13:40]

this line, line 201 and the scope starting in 203 seem to be assuming that the
value of enable_localhost_ice_candidate will always be false.  If that's the
case, can you add a DCHECK at the top of this function?  If it's not the case,
then do we need to set this to false in 203?

[guoweis_left_chromium, 2015/09/16 18:51:03]

Yes, it was initialized to be false in the ctor of
webrtc::PeerConnectionInterface::RTCConfiguration. But adding explicit setting
to false is better.

+    return;
+  }
+
+  if (blink_config.iceServers().isNull()) {
+    // Same as when iceServers is undefined or unspecified.
+    webrtc_config->enable_localhost_ice_candidate = true;
+  } else {
+    for (size_t i = 0; i < blink_config.iceServers().numberOfServers(); ++i) {
+      webrtc::PeerConnectionInterface::IceServer server;
+      const blink::WebRTCICEServer& webkit_server =
+          blink_config.iceServers().server(i);
+      server.username =
+          base::UTF16ToUTF8(base::StringPiece16(webkit_server.username()));
+      server.password =
+          base::UTF16ToUTF8(base::StringPiece16(webkit_server.credential()));
+      server.uri = webkit_server.uri().spec();
+      webrtc_config->servers.push_back(server);
+    }
   }
 
   switch (blink_config.iceTransports()) {
     case blink::WebRTCIceTransportsNone:
       webrtc_config->type = webrtc::PeerConnectionInterface::kNone;
       break;
     case blink::WebRTCIceTransportsRelay:
       webrtc_config->type = webrtc::PeerConnectionInterface::kRelay;
       break;
     case blink::WebRTCIceTransportsAll:
@@ skipping 1401 matching lines @@
 }
 
 void RTCPeerConnectionHandler::ResetUMAStats() {
   DCHECK(thread_checker_.CalledOnValidThread());
   num_local_candidates_ipv6_ = 0;
   num_local_candidates_ipv4_ = 0;
   ice_connection_checking_start_ = base::TimeTicks();
   memset(ice_state_seen_, 0, sizeof(ice_state_seen_));
 }
 }  // namespace content